Electric welding and the like



1,620,206 March 8 1927' L. H. HOFFER ELECTRIC WELDING AND THE LIKE Filed NOV. 21, 1922 L FIE/7 5/4 E 9 F INVENTOR LEROY H HOFF R Patented Mar. 8, 1927.

UNITED STATES ."PA'JIENTI "OFFICE.-

LE BOY 11. Roman, OFNYACK, NEW You, assrenon r0 moms n. IUBRAY, or

' BROOKLYN, NEW YORK.

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Application 11112:! November 21, 1922. Serial No. 802,324.

In a previous application for Patent No. 445,972, (Patent No. 1,436,395 of November 21, 1922) I have described an lmproved apparatus and method for controlling the ap plication of theelectric current in welding, riveting and similar operations. In the apparatus there described an oil switch was used to close the welding circuit and at the same time a secondary circuit was closed by means of an air switch and served to open the oil switch of the welding circuit. Thus I provided for the limitation of the time interval of the welding current to a minimum determined only by the lag in the electrically operated device for cutting off the welding current. My present application is directe to a similar process and apparatus.

The single figure of the accompanying drawing is a diagrammatic view illustrating the mechanism and the circuits involved.-

Referring to the drawing, the electrodes between ivhich the work is to be arranged are indicated at 1 and 2 and are connected to the single coil 3 constituting the secondary of the transformer of which the primary coil 4 is connected to an alternating-current main line terminal 5. and at its opposite end (through suitable connections referred to-be low) to the other main line terminal 6.

A bracket 7 supports a solenoid having a coil 8 and a core 9. The bracket supports an insulated arm 10 connected to the primary coil 4 and carrying at its lower end a contact member 11. The bracket? carries also the pivoted switch arm 12 with a contact 13 adjustable by means of the spring 14 and connected to wires 15 running through a bracket 16 to a wire 17 which is connected to one end of a current transformer 18. the other terother terminal 21 of which is connected by a Wire 22 to a bracket 23 which is electrically connected to a main operating switch arm 24. The opposite end of the coil 8 is connected by a wire 25 to a switch terminal 26 carried on a sup orting board 27 which carries also the brac et 23. It will be seen, therefore, that the pushing forward of the switch arm 24 closes the circuit through the solenoid 8 and causes this to close the welding circuit.

e switch 24 is connected through a link 28w1th the core 29 of a solenoid 30, one ter-- mlnal of which is connected through a wire 31 to a switch terminal 32 in line with the terminal 26. -The opposite end of the coil is connected by a wire 33 with a terminal '34 of a secondary switch arranged to co-operate with a terminal 35 on the end of a wire 36 which is connected by way of the wire 19 with the terminal 20 of the direct current circuit. If the switch 24 were closed, m'akmg contact with the terminal 32, it will be seen that the closingof the switch 34, 35 would complete the circuit through the coil 30. This would pull down the link 28 and open the operating switch.

This switch may be of the type shown in my previous application above referred to in which it is not essential that the entire handle be retracted in order to open the switch, thus permitting the apparatus to act before the operator releases the switch handle. Or the apparatus may be designed to operate so slowly or with such a slight pull on the solenoid 30 as to permit the use of a handle directly connected to the solenoid core.

For closing the switch 34, 35 I use a device which is actuated by the secondary of the current transformer 18. The terminals of the secondary are connected to wires 37 and 38 which lead to a time element relay indi cated diagrammatically by the coils 39, 40 arranged above a disc 41 on a spindle 42 carrying an arm 43 adapted to strike the spring terminal 34 and press it against the terminal 35. The current flows through the coils 39 and 40 in a direction to cause the plate 41 to turn in the direction of the arrow shown thereon, and a coil spring 44 is used to turn it back to its starting point.

The method of applying the invention in,

for example, a welding operation is as fol-- lows. The electrodes are moved together against the work'by any usual or suitable mechanism and are pressed together strongly before the current is applied. The invention is applicable to a variety of welding methods but I prefer that of Murray Reissue Patent No. 15.466, October 10, 1922, in which a current of extremely high ampere 34 and 35 to spring apart.

strength andbrief duration is used. With such a process there is a great advantage in.

the mechanical pressure between the electrodes, the operating lever 24 is pushed forward to engage the contacts 26 and 32. The first efiect is the closing of the direct current circuit through the-solenoid coil 8. This in turn closes-the alternating current welding circuit through the primary coil 4, by closing the switch 11, 13. The secondary circuit of the current transformer 18 is then supplied with current to actuate the relay which closes the direct current circuit through the coil 30 and opens the operating switch. The relay is designed or'may be adjusted to a predetermined time interval. For this purpose various other forms of relay, utilizing the current in the welding circuit to close the circuit of'thc coil 30, may be substituted for the transformer and relay illustrated. When the coil 30 acts to withdraw the operating lever. the switch arm 12 drops and opens the Welding circuit and the relay resets itself, permitting the contacts The machine is now ready for another cycle of operations.

The fact that the welding circuit is closed by a solenoid and that the operating lever has only to close the solenoid circuit simplifies the switching mechanism as compared with that of my previous application above referred to. The control of the secondary circuit, by which thecurrent is cut off, facilibriefest total time intervals. Instead of the solenoids illustrated it will be understood that various other electrically controlled devices may be used for actuating the switches.

4 in the arrangement of the parts may be made by those skilled in the art without departure from the invention as defined in the following claims.

What I claim is- 1. An apparatus for electri welding including in combination a-main welding circuit. means controlled by one auxiliary electric circuit for closing the main welding circuit and means controlled by a second elec tric circuit for opening the main welding circuit by de-energizing the first auxiliary circuit, and a timing device controlling the second auxiliary circuit.

2. An apparatus for electric welding including in combination a main welding circuit, means controlled by one auxiliary electric circuit for closing the. main welding circuit and means controlled by a second electric circuit for opening the main welding circuit by de-energizing thefirst auxiliary circuit. and a timing device controlling the second auxiliary circuit, said timing device being actuated from the main welding cir-' cuit.

In witness whereof, I have hereunto'signed my name.

Y LE ROY H. HQFFER.

interval within a small fraction of a second wlnle permitting the employment of the very 

